Design Trade-offs between Series-Peaking Inductor and High $f_T$ SiGe HBTs in Transimpedance Amplifiers

Series-peaking inductor is a crucial block in a shunt-feedback Transimpedance amplifier (TIA) used for bandwidth enhancement. Achieving high-quality factor (Q) and high self-resonant frequency (SRF) of on-chip inductors is challenging for large bandwidth TIAs. A higher $f_T$ heterojunction bipolar transistor (HBT) can relax the requirement of series-peaking inductance. Due to the lower inductance value, a high $Q$ and high SRF can be achieved. This paper presents design trade-offs between the series-peaking inductor and HBT device parameters using two different GlobalFoundries SiGe BiCMOS processes 9HP+ (90nm Bulk) and 45nm SiGe (45nm RFSOI). The simulation and measurement results are shown to validate the trade-offs. Measurements show that 45nm SiGe TIAs have 15-25% more bandwidth than 9HP+ TIAs, with a 14-30% reduction in inductance across various device sizes.